Physical Functioning in Female Caregivers of Children With Physical Disabilities Compared With Female Caregivers of Children With a Chronic Medical Condition

From the Department of Pediatric Physical Medicine and Rehabilitation, University of Michigan, Ann Arbor (Drs Tong and Haig and Ms Yamakawa); Fremont Orthopaedic Medical Group, Fremont, Calif (Dr Kandala); and the Section of Pediatric Physical Medicine and Rehabilitation, Department of Physical Medicine and Rehabilitation, University of Michigan, Ann Arbor (Dr Nelson); and the Department of Symptom Control and Palliative Care, University of Texas M. D. Anderson Cancer Center, Houston (Dr Shin).

ObjectivesTo evaluate if physical functioning is different in female caregivers of children with physical disabilities compared with female caregivers of children with nondisabling medical illnesses, and to investigate the factors associated with functioning level.

DesignCross-sectional survey.

SettingUniversity-based clinics.

PatientsNinety consecutive female caregivers of children presenting to a pediatric physical medicine and rehabilitation (PM&R) clinic, and 23 presenting to a pediatric endocrine clinic.

InterventionFifteen-minute self-administered survey.

Main Outcome MeasuresThe dependent variable measured was physical functioning (physical functioning subscale of the Short Form-36). Independent variables measured were the average back pain severity over the last week (100-mm visual analog scale), mood (using the Center for Epidemiologic Studies–Depression Scale), work status, amount of lifting at work, caregiver demographics, child demographics, and the physical functioning ability of the child (measured using the WeeFIM scale).

ResultsThe mean (SD) physical functioning score of caregivers of children in the pediatric PM&R clinic was 80.6 (21.9), which was less than the score of 90.2 (17.6) for caregivers in the pediatric endocrine clinic (mean difference, 9.6; 95% confidence interval, −0.9 to −18.4). The physical functioning score of 77.7 (22.9) in caregivers of PM&R clinic children with a WeeFIM scale score of 1 to 4 was significantly worse than the 90.5 (14.8) in female caregivers of children with a WeeFIM score of 5 to 7 (mean difference, 12.8; 95% confidence interval, −2.0 to −23.6). This decrease is associated with the average pain severity, mood, and total length of time of back pain in the previous 12 months. Regression analysis shows that pain severity and caregiver mood are significantly related to the physical functioning status of the caregiver.

ConclusionsPhysical functioning is decreased in female caregivers of children with a physical disability. This decrease is associated with caregiver pain severity and mood.

ONE OF THE SPECIFIC objectives of the Healthy People 2010 initiative is to reduce the number of people with disabilities in institutions.1 If caregiver burden in informal caregivers of children with physical disabilities is overwhelming, it may lead to the institutionalization of these children being cared for.2 The issue of physical functioning in caregivers of children with physical disabilities needs to be addressed because of the physical nature of the caregiving.

Caregiver burden has been shown to be a significant problem under many different circumstances.3 This includes caring for patients with dementia,4,5 cancer,6 and burns,7 as well as children with disabilities8 and brain injury.9,10 These studies have investigated the psychological aspects of caregiver burden such as stress, depression, and social isolation. However, there have been few studies evaluating the physical aspect of caregiver burden. Although one study investigated the contribution of the physical demands of caregiving to caregiver burden, it did not address physical functioning as an end point.2 The goals of the present study are to investigate the physical functioning level in female caregivers of children with physical disabilities and to investigate which risk factors affect physical functioning in this group.

METHODS

SUBJECTS

In a university pediatric physical medicine and rehabilitation (PM&R) clinic and a pediatric endocrine clinic during the 2000-2001 period, consecutive adult female caregivers meeting eligibility criteria were invited to be study subjects. In the pediatric PM&R clinic, subjects were excluded for the following reasons: caring for another child needing assistance with transferring to and from a bed, previous back surgery or fracture, age younger than 18 years, any child in the caregiver's own family younger than 2 years old, or caring for any child having diabetes mellitus. In the pediatric endocrine clinic, subjects were excluded for the following reasons: caring for a child needing assistance with transfers, previous back surgery or fracture, age younger than 18 years, or caring for any child younger than 2 years old in one's own family. Having a child younger than 2 years old was an exclusion criteria since most children younger than 2 years old need to be carried. A history of back surgery or fracture was an exclusion criterion since this factor would probably affect physical functioning. The pediatric endocrine clinic was chosen as the control clinic since most endocrine problems are not physically disabling but still require significant medical care and attention. The study was limited to females since most informal caregivers of children seen in the pediatric PM&R clinic are female. Institutional review board approval was obtained prior to initiation of the study. Face-to-face informed consent was obtained from the subjects and documented at the clinic visits prior to administration of the survey.

SURVEY INSTRUMENTS

A 15-minute, self-administered survey was provided to each subject during a clinic visit. This survey included child demographics (eg, height, weight, age, and sex) and caregiver demographics (eg, height, weight, age, race, and marital status). The following questionnaires were administered. The Standardised Nordic Questionnaires,11 a series of 8 questions concerning whether the subject has low back pain (LBP), the severity of LBP, and the frequency of LBP. The first question asking if the subject has LBP was modified into 2 questions asking if the subject had LBP prior to the birth of her child who was now in clinic and after the birth of her child now in clinic. Two other specific questions used in the data analysis include: "Have you ever been hospitalized because of low back trouble?" and "What is the total length of time that low back trouble has prevented you from doing your normal work (at home or away from home) during the last 12 months?"

Pain severity of the average pain in the last week was assessed with the use of the 100-mm visual analog scale (VAS), where 0 indicates no pain and 10 indicates the worst pain imaginable. This scale is commonly used in pain studies and has been validated.12

Mood was measured by the Center for Epidemiologic Studies–Depression Scale (CES-D Scale). This comprises 20 four-category Likert questions, and the total score (0-60) is the sum of each individual question's score.13,14 It is valid among persons with physical disabilities15 and has concurrent validity with the Diagnostic and Statistical Manual of Mental Disorders, Revised Third Edition (DSM III-R) diagnoses of depression among patients with chronic pain with a limit of 19 for depression.16

Physical functioning was measured by the physical functioning subscale (PFS) of the Medical Outcomes Study 36-Item Short-Form Health Survey Questionnaire (SF-36).17 This subscale comprises 10 three-category Likert questions regarding the subject's ability to do different activities such as walking, going up the stairs, bathing and dressing, or moderate (eg, operating a vacuum cleaner) or strenuous activities (eg, running or strenuous sports). The final percentage score is the sum of each individual question score divided by the total possible score multiplied by 100.

Physical functioning of the child was measured by the ability of the child to transfer using the WeeFIM scale. The WeeFIM scale is a 7-point ordinal scale ranging from 1 (needing total assistance with transfers) to 7 (complete independence with transfers). The WeeFIM score of 4 (minimal assistance) is important since that is the first category where the child needs assistance with transfers. This scale has been validated for stability and has also been shown to have good interrater reliability.18,19

Body mass index (BMI) was calculated as weight in kilograms divided by the square of height in meters (BMI = weight/height2).

DATA ANALYSIS

A t test of 2 independent proportions was used to determine if the physical functioning of the subjects in the pediatric PM&R clinic was different from that of the female caregivers in the pediatric endocrine clinic. This was also used to determine if the physical functioning of the subjects whose child needed help with transfers (WeeFIM scale score, ≤4) was different than the physical functioning of the subjects whose child did not need help with transfers (WeeFIM scale score, ≥5).20 This analysis comparing the group whose children needed help with transfers with the group whose children did not need help was repeated in the pediatric PM&R subjects to examine this relationship in the subgroup of caregivers of children with physical disabilities.

To ensure that demographic variables were not associated with the PFS subscale score of the subjects, the Pearson correlation coefficient compared the PFS score with the continuous demographic variables and the Spearman correlation coefficient compared the PFS score with the categorical variables.20 Any factor that was significantly associated was controlled for in the regression analysis comparing the PFS with the predictive variables.

To determine if physical functioning was associated with the independent variables and if there was any collinearity between the data, an initial bivariate analysis using the Spearman rank-order correlation coefficient was used comparing the PFS score with the average pain severity VAS, CES-D, total length of back pain over the past 12 months, and BMI. P<.01 was considered significant.20 Using the PFS as a dependent variable, stepwise multiple linear regression analysis was performed.

POST HOC SUBGROUP ANALYSIS

Since there were 4 subjects who were not mothers, it was felt that applying the results of this study to mothers may be invalid. To address this, the analyses above were rerun excluding the 4 subjects.

RESULTS

Ninety consecutive subjects in the pediatric PM&R clinics participated, and 6 eligible subjects who were approached refused owing to time commitments. Twenty-three consecutive subjects in the pediatric endocrine clinics participated (recruitment started later and was slower in the pediatric endocrine clinic), and 2 eligible subjects who were approached refused owing to time commitments. The demographics of all 113 subjects are listed in Table 1.

The PFS score of the 90 subjects in the pediatric PM&R clinic (mean [SD], 80.6 [21.9]) was significantly worse than that of the subjects in the pediatric endocrine clinic (mean [SD], 90.2 [17.6]) with a mean difference of 9.6 (P = .03; 95% confidence interval [CI], −0.86 to −18.4) as shown in Table 2. The PFS score of the 70 subjects whose children needed assistance with transfers (mean [SD] 77.7 [22.7]) was also worse than the PFS of the 42 subjects whose children did not need assistance with transfers (mean [SD] 90.6 [16.3]) with a mean difference of 12.9 (P = .002; 95% CI, −4.9 to −20.8). A similar relationship was found when a subgroup analysis of the caregivers in the pediatric PM&R clinic whose children needed assistance with transfers was compared with caregivers in the pediatric PM&R clinic whose children did not need assistance with transfers (Table 2).

Correlation Coefficients Between the PFS* Score and Demographic Variables

The average pain VAS score in the last 7 days (P<.001), the CES-D Scale score (P<.001), and the total length of time of back pain in the previous 12 months (P<.001) were significantly associated (Table 4) with the PFS score by the Spearman rank-order correlation coefficient.

Stepwise multiple linear regression showed a significant correlation between the PFS score and the average VAS pain score in the last 7 days (β = −4.4, P<.001) and the CES-D Scale score (β = −0.5, P = .007), while the total length of time of back pain in the last 12 months (β = −0.11, P = .37) and BMI (β = −0.11, P = .18) were not statistically significant. There were no significant collinearity problems (variance inflation factor for the VAS pain score was 1.1 and for the CES-D Scale score was 1.1) and no interaction was found (P = .83) between the effect of the VAS pain score and the CES-D Scale score on physical functioning.

POST HOC SUBGROUP ANALYSIS OF MOTHERS

When the 4 subjects who were not birth mothers were excluded from the analysis, the PFS scores of the mothers in the pediatric PM&R clinic (mean [SD] 81.0 [21.7]) were less than the PFS scores of the mothers in the pediatric endocrine clinic (mean [SD] 90.2 [17.6]), and this difference was statistically significant (mean difference, −9.2; 95% CI, −17.9 to −0.4). The PFS score of the 67 mothers of children needing assistance with transfers (mean [SD], 78.5 [22.5]) was also significantly less than the PFS score of the 41 mothers of children not needing physical assistance with transfers (mean [SD], 90.4 [16.4]) with a P value of .004 (mean difference, −11.9; 95% CI, −19.9 to −3.9). Subgroup analysis of mothers of children in the pediatric PM&R clinic showed that the PFS score of the 66 mothers of children needing assistance with transfers (mean [SD], 78.4 [22.7]) was significantly less than the PFS score of the 19 mothers of children not needing physical assistance with transfers (mean [SD], 90 [15]) with a P value of .04 (mean difference, −11.6; 95% CI, −22.6 to −0.5). The correlation coefficients comparing the demographic variables to the PFS score were not significant and similar to the data shown in Table 3.

The average pain VAS score in the last 7 days (P<.001), the CES-D Scale score (P<.001), and the total length of time of back pain in the previous 12 months (P<.001) were significantly associated to the PFS score, which is similar to the results seen for the whole group.

Stepwise multiple linear regression showed a significant correlation between the PFS score and the average VAS pain score in the last 7 days (β = −4.5, P<.001) and the CES-D Scale score (β = −0.45, P = .02), while the total length of time of back pain in the last 12 months (β = −0.14, P = .29) and BMI (β = −0.09, P = .32) values were not statistically significant. There were no significant collinearity problems (variance inflation factor for the VAS pain score was 1.1 and for the CES-D Scale score was 1.1) and no interaction was found (P = .97) between the effect of the VAS pain score and the CES-D Scale score on physical functioning.

COMMENT

There is a significant body of literature dedicated to studying the burden placed on caregivers of both elderly persons and children with disabilities. However, most of these studies have focused on the psychological aspects of caregiver burden such as stress, depression, and social isolation.

This report is an initial study on caregiver burden from a physical functioning perspective. The first research question is to determine if physical functioning in female caregivers of children with physical disabilities is decreased. This study shows significantly decreased physical functioning in female caregivers of children with physical disabilities compared with female caregivers of children with a nonphysically disabling medical problem. There is an even more significant decrease when the child needs physical help with transfers.

The second research question is to determine which factors are related to the PFS in female caregivers of children with physical disabilities. This study also shows that a decrease in physical functioning is related to both back pain severity and mood, which is consistent with the literature on physical functioning in occupational and chronic pain settings. It has been shown that physical functioning in subjects with chronic LBP is worse than in the general population.21 Back pain has also been shown to be a significant cause of disability, accounting for an estimated $11.3 billion in annual direct medical costs.22 A relationship between caregiving and back pain has been noted.23 Depression also decreases physical functioning.24 Treating these factors may improve the physical functioning of these caregivers and decrease the risk of the child's becoming institutionalized.

This subject population is unique from the occupational pain population since there are no overlying worker's compensation or litigation issues that may affect the subjects' physical functioning. This suggests that the decreased physical functioning is truly related to both the subjects' pain and mood when confounders such as litigation issues are not present.

There are several strengths to this study. To our knowledge, this is the first project evaluating the physical aspect of caregiver burden in caregivers of children with disabilities. Caregivers of children with nondisabling medical illnesses is a more appropriate control group than using caregivers of healthy children would have been since this helps control for recall bias and other factors related to caring for medically ill children (eg, stress, guilt, or the supervision of a medical regimen). Another strength of this study is the use of previously validated survey instruments.

There are several limitations to this study. The cross-sectional design shows a significant correlation between variables but does not prove a causal relationship. This study also relies on self-reporting by the caregivers, which may be biased. Lastly, this study excludes subjects with more than 1 child with a physical disability. This is because clinically it was noted that parents who have more than 1 child with physical disabilities are often foster mothers. This group is likely different from the rest of the clinic female caregiver population.

CONCLUSIONS

Caregiver burden in caregivers of children with disabilities, especially the physical aspects, has been understudied. This initial study shows that physical functioning in female caregivers of children with physical disabilities is significantly decreased when compared with caregivers of medically ill children. It also shows that physical functioning may be related to pain severity and mood. Future studies should further evaluate the factors contributing to caregiver burden and consider possible alleviating measures.

The study was supported in part by Rehabilitation Research Training grant NIDRR H133P990014 from the University of Michigan Health System/Michigan State University/Ann Arbor Center for Independent Living (Dr Tong), and by University of Michigan Medical Rehabilitation Research Training Program grant T32 HD07422-10 from the National Institutes of Health (Dr Tong).

The current literature looking at caregiver burden has primarily examined psychological factors (eg, mood, stress, and social isolation) in caregivers of children with disabilities. To our knowledge, this is the first study to look at the physical functioning aspect in caregivers of children with physical disabilities. It shows that physical functioning is decreased and is related to certain risk factors. Treating these factors may improve physical functioning and decrease the risk of these children being institutionalized.

US Department of Health and Human Services, Disability and secondary conditions. Healthy People 2010: Understanding and Improving Health. 2nd ed. Washington, DC US Dept of Health and Human Services November2000;chap 6. Also available athttp://www.health.gov/healthypeople/Accessed September 9, 2002